XKB: XkbCopyKeymap: Don't leak all the sections

Previously, we'd just keep num_sections at 0, which would break the
geometry and lead us to leak sections.  Don't do that.
(cherry picked from commit 0137b0394a)

xkb/xkbUtils.c

@@ -1770,6 +1770,7 @@ XkbCopyKeymap(XkbDescPtr src, XkbDescPtr dst, Bool sendNotifies)
             if (!tmp)
                 return FALSE;
             dst->geom->sections = tmp;
+            dst->geom->num_sections = src->geom->num_sections;
 
             for (i = 0,
                   ssection = src->geom->sections,